Field of Invention
The present invention relates, in general, to forming a structure on or around a body part of an animal or human being. More specifically, it relates to the field of orthopedic splinting materials, methods and apparatus. Described herein is also a method of using a novel wood-plastic composite as a splint/cast in immobilization of a fractured body part and a kit thereof.
Description of Related Art
In cases of bone fracture a splint may be applied for supporting or immobilizing a body part. Such a splint is usually wrapped with an elastic bandage and the rigid portion does not envelope the limb circumferentially. Traditional splinting techniques use a variety of materials including plaster of Paris (used first time in the Crimean war 1854 in treatment of battle wounds), fiber-glass reinforced polyurethane (DE 26 51 089), alumafoam (U.S. Pat. No. 4,213,452 and U.S. Pat. No. 4,153,051; an aluminium strip padded on one side with sponge-like foam) and complex pre-formed multilayer systems containing a plurality of straps, hooks etc. (WO 2008/041215, EP 0 393 003, EP 0 407 055).
Common to all of these techniques is that they are moldable to an extent during setup. Furthermore, depending on the applied technique the time period of mouldability followed by subsequent hardening varies greatly.
Use of the traditional splint material plaster of Paris is decreasing, despite its low costs. This is mainly due to its many well known disadvantages e.g. long setting and drying times, messy application, low strength and relative heaviness which can be quite considerable, thus limiting movement, especially of a child. Further on, during application of the plaster bandage, the user has to be extra careful for avoiding making indentations in the soft plaster that could cause local areas of high pressure leading to the formation of plaster sores. The main reason why it is still used in some casting applications is its excellent molding properties.
Fiber-glass reinforced polyurethane resin based splinting materials are considered a practical alternative for the conventional plaster of Paris casts and are currently widely used in the treatment of fractured body parts. These materials are lightweight, durable, waterproof and they tend to have a shorter setting time than traditional plaster-based materials.
Despite these advantages they are far from being ideal casting material. They require several layers for weight-bearing casts; they may crack from repetitive use and may leave sharp edges, potentially causing excoriation of the skin. The polyurethane resin based materials are quite resilient for which reason they do not conform well to the extremity. In addition, for avoiding wrinkle formation during application the extremity must be in the correct position. Further, glassfiber/polyurethane casting materials contain toxic or harmful components (cyanates and fibre-glass) and have to be applied with protective gloves. According to the MSDS of some fiber reinforced casting materials, skin contact with material during applying may cause itching, redness, dryness etc.).
Activations of the plaster-of-Paris and glassfiber/polyurethane based casting materials are based on a chemical reaction initiated with water. As a result, the hardening process of polyurethane based splints (U.S. Pat. No. 4,376,438) and of Paris (WO 00/35501) cannot be stopped or paused once the reaction has started. Therefore if there is any delay in setting of the casting application it will lead to drying of the casting material and it has to be replaced with new one. Whatever the development steps for these casting materials are they still contain toxic and irritating components, such as cyanates and calcium sulphate hemihydrates. Therefore it is very important that when a cast of the known materials is applied, all bony prominences are adequately padded for avoiding cutaneous complications.
An ongoing trend in developing alternative splinting materials is to try to use materials which are do not involve chemical reactions of toxic components and requires only heat treatment before use. One example of such a material is presented in U.S. Pat. No. 4,240,415. This material is based on electron radiated polycaprolactone. It can be heated in boiling water to give it pliable properties followed by hardening when cooling to room temperature. These types of materials are recommended for use in splints requiring revisions or functional positioning, especially in radiotherapy patient positioning and immobilization. However, they lack good molding properties and sufficient rigidity to be used in splinting of extremities.
The rigidity and usability of polymer based splinting materials have been improved by manufacturing composite materials comprising combinations of reinforcing natural fiber component and thermoplastic polymers (US 2008/0262400, US 2008/0154164, WO 94/03211, EP 0 393 003). These publications disclose polymers e.g. polycaprolactone or polyhexamethylene adipate compounded with short-fibred cellulosic additives having grain size of up to a several hundred microns are used to make up complex, preformed splinting systems. The fine particulate fillers improve the handling properties and stiffness of the formed composites. It should be pointed out that a still rather complex structure, such as a mesh of elements, with a plurality of specially designed openings and straps for fastening, is required in order to achieve an overall rigid splinting system.
It is an object of the present invention to eliminate at least a part of the problems related to conventional splinting systems and the above-mentioned problems of current products related either to their toxicity, complexity of structures or insufficient rigidity for splinting the limbs and body extremities.